Regensburg 2007 – scientific programme
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EP: Fachverband Extraterrestrische Physik
EP 7: Solar-Terrestrische Beziehungen
EP 7.4: Talk
Tuesday, March 27, 2007, 17:15–17:30, H46
Toward understanding the rise profile of coronal mass ejections — •Bernhard Kliem1, Tibor Toeroek2, Christopher Elmore3, Carolus J. Schrijver3, and Alan M. Title3 — 1Astrophysikalisches Institut Potsdam — 2Mullard Space Science Laboratory, University College London — 3Lockheed Martin Advanced Technology Center, Palo Alto, USA
The nature of the rapid, nonlinear rise of erupting prominences that evolve into fast (700 km s−1) coronal mass ejections has been the subject of intense study. Exponential and power-law rise profiles were successfully fitted to various observations, but the quality of the height measurements has so far been insufficient to permit a distinction between the two laws. Theory predicts an initially exponential rise if the eruption is driven by an instability, and indicates a power-law rise after a catastrophic loss of equilibrium.
We present a detailed analysis of two filament eruptions observed with high precision in the EUV by the TRACE satellite. In both cases the morphology of the eruption suggests the action of the torus instability but a power law with an index near 3 gives a better fit than an exponential. We found, both semi-analytically and in MHD simulations, that a substantial initial velocity can modify the expansion profile of the instability such that it gets closer to a power law (with the fitted index value) than to an exponential in the observed range. While this agreement is encouraging, the result undermines the hope that the good coverage of rise profiles, expected from combined TRACE and STEREO data, will permit a distinction between the models.